The user interface for web-browsers often include tabs, where each tab represents a different web page or document that the user has accessed. Many browsers may use a single process to run the browser and tabs, yet some browsers are multi-process, so that each tab runs as a separate, sandboxed process. Browsers having such a multi-process environment generally include a main process, or browser process, that controls all the other processes, in a star-like pattern. In a sandboxed, multi-process browser, the child processes (or tabs) do not communicate with each other. This provides a more secure web-surfing environment because what is happening in one tab cannot access or affect the contents of another tab or the computing device in general.
A webview tag is a mark-up language element that allows a web page to embed another web page or other document. Embedded web pages, for example from a browser tag or a similar elements, such as an iframe, have been available for traditional browsers, but not running as an independent process in a sandboxed, multi-process browser. This is because the embedded web page, also known as the guest, runs as its own process, and, therefore, should not be able to communicate directly with the embedder web page and vice versa to maintain the sandbox for each process. But the embedder web page may need to send events to the guest to properly embed and render the guest within its content. Events represent user-interaction with the document, such as scrolling, mouse clicks, etc.